The present invention relates to a stress inducible promoter. Particularly, it relates to a new genomic gene coding a peroxidase isoenzyme of Ipomoea batatas and a promoter thereof whose expressions are strongly induced under environmental stresses in the cultured cells and whole plants.
The whole or part of the peroxidase gene promoter of the present invention can be effectively used to develop stress-tolerant plants, resistant to the environmental stresses, and to develop transformed organisms producing useful materials on a large scale.
When the most organisms including plants are exposed to various environmental stresses generated according to the environmental aggravation of earth as well as biological stress of bacteria, insect and virus, oxygen which is necessary for keeping life changes into reactive oxygen species of superoxid anion radical, hydrogen peroxide and hydroxyl radical that induce serious physiological disorder. Therefore, there are many systems in the body to get rid of these reactive oxygen species such as the macromolecular antioxidative enzymes of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and small molecular antioxidative materials of vitamin C, vitamin E and glutathione.
It has been well known that peroxidase widely exists in plant cells as a reducing enzyme which reduces hydrogen peroxide in the presence of electron donor. Peroxidase is becoming the center of interest since it has an important role for plant to react on the various external stresses and is an industrially important enzyme by being used as various clinical test reagents because of its sensitive enzyme reaction. Generally, the activity of plant peroxidase is increased by the various environmental stresses and, particularly, is very high in the cultured cells which are considered to be grown under the high oxidative stress. It has been reported that the cultured cell of Ipomoea batatas produces peroxidase on a large scale than any other cultured cells of plant (Phytochemistry, 39, 981-984, 1995).
The genes coding peroxidase isoenzymes of the some plants that are originated from about 20 species plants of horseradish, barley, wheat, rape, tobacco, spinach and rice have been reported. The present inventors have isolated the peroxidase gene of Ipomoea batatas for the first time. We have reported that the anionic peroxidase swpa1 and neutral peroxidase swpn1 isolated from the cultured cells of Ipomoea batatas are specifically expressed in the cultured cells and stem of Ipomoea batatas, and plurally exist in genome (Mol. Gen. Genet., 255, 382-391, 1997). It has also reported that peroxidase can be produced on a large scale by transforming the whole or part of these peroxidase genes to plant organisms and cells (Phytochemistry, 47, 695-700, 1998; Phytochemistry 48, 1287-1290, 1998).
In addition, the present inventors have found out the nucleic acid sequence of the anionic peroxidase gene swpa2 (GeneBank Accession NO. AF109124) and swpa3 (GeneBank Accession No. AF109123) from Ipomoea batatas. According to this, swpa2 has 71 signal peptides, swpa3 has 66 signal peptides, and swpa2 and swpa3 have 1245 and 1310 bp of nucleic acid sequences coding 358 and 349 of amino acids, respectively. The isoelectric point of mature protein expressed by swpa2 and swpa3 is 4.1 and 4.3, respectively, and this shows that all the genes code the anionic peroxidase. AAUAA of typical polyadenylation signal and poly(A)-tail exist in the 3xe2x80x2-untranslated region of swpa2 and swpa3, and particularly, the N-terminal sequence of swpa2 gene is completely same as that of major isoenzyme (A-2) from the cultured cells of Ipomoea batatas. In addition, the present inventors have demonstrated that swpa2 gene is strongly expressed in response to wounding, low temperature or ozone treatment in the leaf of Ipomoea batatas, on the other hand, swpa3 gene is weakly expressed in response to wounding, but strongly expressed by low temperature or ozone treatment (Mol. Gen. Genet., 261, 941-947, 1999).
It is an object of this invention to provide a genomic peroxidase DNA originated from Ipomoea batatas and nucleic acid sequence thereof.
It is a further object of this invention to provide a promoter of which expression is strongly induced by the various environmental stresses.
It is an additional object of this invention to provide transformed organisms that are resistant to the various environmental stresses and a preparing method thereof.
It is also an object of this invention to provide transformed organisms that are capable to produce useful materials on a large scale and a preparing method thereof.